Cast shadow on hidden object in eevee
I've started with a simple scene, and this node setup (a standard diffuse is currently connected so we can see the default lighting effects)



If you connect the other node setup, you might see something like this, depending on the placement and power of your lights (Note: make sure alpha blend is enabled for the shadow catcher material);



Say you've adjusted this multiple value, but the shadow is too light;



Move this slider up...;



And turn up this value;